Spatiotemporal Changes in Supply–Demand Patterns of Carbon Sequestration Services in an Urban Agglomeration under China’s Rapid Urbanization

Round 1

Reviewer 1 Report

2.Major concerns:

2.1 The authors has mentioned the limitations of the estimation of CO2 emission based on nighttime light data (Sect.4.4). The reviewer think it not enough to say this limitation ‘had little impact on the results’ without any quantitative analysis and without any effort to correct or compensate the offset. Please try to do some solid work, because knowing the exact uncertainty of the data we use is the prerequisite of any statistic work.

2.2 Scientific researches in carbon neutrality are quite needed ,giving the credit that they can help policy makers and local government get efficient suggestions. The review found the policy suggestions in Sect.4.3 were quite usual, without real suggestions that the local government of HCUA can follow.

2.3 About the structure of the manuscript. The authors gave some future work suggestions in Sect.4 and then followed by some rough conclusions as Sect.5. This structure makes the reviewer kind of confused with the logic. The authors are suggested to combine the two sections, giving the conclusions and then some future work suggestions.

 

3. Specific comments

1)The sequencing of the figures are wrong, Fig 4 is missing! Re-check the number of the figure and also the figure mentioned in the paragraph.

2) The manuscript should be prepared with line number at left column, or it is difficult to point out the problems and their locating lines.

3) in Sect3.1, the author cited Fig 3 and Fig 6a in the 1st paragragh, which is not regular way. The sequencing of the figures should be continuous, like Fig 3 and Fig 4.

4)in Sect3.2, in the second line of the 1st paragragh, Fig.4-a->Fig.4a, though the fact is that the figure 4 is missing.

5) Several figures in the manuscript are blurry, like Fig 6,Fig 11. Figures with better resolution are recommended.

6)’Harbin-Changchun agglomeration’ are used for several time in Sect.4, unlike the expressions in  most cases in the manuscript.  Unified expression is suggested, like HCUA.

7)in Sect4.2, at the end of the 1st paragragh, ‘the region was sparsely populated and energy and industrial sectors were small in scale;’ should be rewritten.

8)in Sect4.2, in the middle of the 2nd paragragh, ‘causing the conversion tofarmland to gradually exceeded the conversion from’ should be rewritten. This is not the normal way to express the intention of the authors.

9)in Sect4.4,at the end of the 3rd paragragh, ‘and flow rate of service flow by establishing a mathematical’ should be rewritten.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The work is a study of the spatiotemporal changes in the supply and demand patterns of carbon sequestration services in a region of Chile. The study is well conducted, and the results will be significant and important for further consideration. The text is well written and easy to read.

The reviewer has no comments to improve the manuscript.

Author Response

Thank you very much! Happy new year!

Reviewer 3 Report

Authors discuss the carbon balance using NEE obtained from satellites as the supply and CO2 emissions from energy consumption as the demand. The authors intend to revise CO2 emissions using nighttime light data, which can still be a valid step even though many emissions are introduced with this factor already in mind. However, the formula utilized by the authors in calculating the supply-demand ratio is not clearly explained, resulting in an unreliable subsequent analysis. The comments in detail are as follows:

(1) Please give the resolution of CO2 emission data, and if there is a difference between the resolution and the nighttime light data, how to unify the resolution of both?

(2) Please explain specifically the meaning of equation (1) and why it needs to be divided by the mean of Smax and Dmax? This is an important issue that relates to the correctness of the whole text.

(3) Is it correct to use them both to represent supply and demand when there is a difference of magnitude between NEE data and emissions (e.g., Figure 6)?

(4) Figure 4 is missing

(5) As the authors state and Figure 8 shows, carbon uptake in terrestrial ecosystems exceeds emissions in the HCUA region, is this conclusion clearly testified to by other papers or can the authors provide verification data? My impression is that vegetation is sparse in urban areas and energy emissions are high, so why this seemingly discordant conclusion?

(6) Is there a basis for the 5-level classification in Table 2? As it relates to policy recommendations in section 4.3.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 4 Report

The paper “Spatiotemporal Changes in Supply-Demand Patterns of Carbon Sequestration Services in an Urban Agglomeration under China’s Rapid Urbanization” touches on the topic of quantifying urban supply and demand for carbon sequestration services. This is very important for formulating effective governmental policies on the way to carbon neutrality. In their research the authors investigate balance between carbon supply and demand within large Harbin-Changchun urban agglomeration (HCUA) located in Northeast China and included different man-made and natural landscapes.

To assess carbon supply authors use data on the net primary productivity (NPP) derived from MOD17A3 data products with a high spatial resolution. For estimating the carbon demand Net Primary Production (NPP) VIIRS nighttime light data was used. Using of these 2 orbital products gave rise to submit this paper to Remote Sensing Journal

Although the paper looks logic and has a clear idea, it is quite difficult to read it. Captions for most of figures are very small, and differences between maps for years under consideration are really minor to see them. Text is also quite complicated for understanding especially in part of results interpreting. The conclusions are likely to be important to assess regional carbon balance changes under anthropogenic influence.

It is not clear if climate change contributes to the regional supply and demand balance. 8 years is not so small term to ignore this agent. Probably, to include meteorological data analyses for considered period (at least averaged values of temperature, humidity and solar radiation for 2012, 2017 and 2020) would be interesting. The information about governmental efforts aiming to sequestrate carbon in HCUA is quite common to attribute all observed changes only to man-made factor. The climate change impact in such region may be compatible with anthropogenic one.

References list consists of mostly papers of Chinese researchers. Does it mean that this topic is not interesting for the world scientific community? It would be good to add there more researches beyond China if there are any. This would show that the paper has not only regional importance.

As a supplementary materials CV of one of the authors is attached that is hardly can be considered as a good idea. More information about data used (especially VIIRS nighttime light data) and verification of models would be appropriate instead.

So, I believe that the manuscript has a potential to be published in RS but requires significant improvement.

 Other remarks

Lines 123-125 – for what period is the urbanization rate pointed out?

 Lines 139 and 140 – Abbreviation PSN should be revealed

 Table 1. - Type of MOD17A3 data should be specified

 Figure 2. - It is very difficult to see the difference between a), b) and c). I don’t think that all 3 figures are needed. There is a mistake in word “higher” in the legend

 Figure 5. - The same as for Fig. 2. It is impossible to see the difference by naked eye. There is an impression that lowest demand area is much larger than 70%.

 Figure 6 (as well as 9b and 11). – It is hardly correct to built trends based on 3 points. I would replace “trends” by “temporal variations” or by something similar.

 Figure 6d – It is impossible to make out grades of demand besides the lowest. I guess that table with values are enough to demonstrate the proportion of demand. It is clear from this Figure that lowest demand for all landforms is close to 100% as I indicated for Fig. 5.

 It is very difficult to read the captions for most of figures. The smallest fonts should be increased.

Figures 8 and 10 – the same as for Fig. 2 and 5. It is really difficult to notice changes of 1-2%.

 Figure 9b – Unlike other cities carbon deficit area proportion for Changchun had grown quite fast. This phenomenon should be explained.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

• This revised version of the manuscript has been improved and is recommended for publication.

Reviewer 4 Report

Authors had corrected the manuscript as it was possible, so I believe it can be published in the current view